Looks like they might be long-haired.
If I were a kitty foster I would end up with 20 cats as I could never give them up.

I'm relieved that they have gone back!

Seriously, you learn to say goodbye to them. We always need more people to foster animals!

If so, how do they adjust?
I've thought about being a foster after I retire in a few years, but our 2 kitties seem very happy and well adjusted and I'd hate to change that.

Two are females and older, 13 and 11. When they first saw kittens in the house they would hiss, but now they kind of ignore them for the most part. It's like, "Oh this again..."

I always keep the kittens in their own area until they are maybe six weeks old. By then I know that they aren't contagious and are litter box trained. Always keep them in a room with the door shut at night.

When I have small kittens I keep them in my small laundry room off the kitchen. Then allow them out into the kitchen during the day, with a piece of cardboard keeping them from going into the rest of the house. When about six or seven weeks they are allowed, with supervision, to go into other areas of the house. And the females just hiss and walk away.

Alternatively, if I have larger kittens or a mother with kittens, I use a spare bedroom upstairs. But with little ones it is so much more convenient to be just off the kitchen, near the microwave for heating formula, etc. I customize for each set of kittens/cats.

Our two year old male orange cat is a different story! He loves "his" kittens and will play with them as if he's one of them. And will also cuddle with and groom them once they are allowed to mix. Right now, though, he hisses at these three week olds. He doesn't understand what they are, maybe. Once they are about six weeks old, they are a lot more like miniature cats and he can relate.

If you have enough space in your house so that your cats can go to a safe spot and not be bothered by kittens, that would work well. Mostly the kittens mind their own business and aren't concerned about the adults.

just to tell who's who.

Not safe to leave them alone with collars at three weeks. But telling who is who is a challenge. For example: I'm bottle feeding, and in order to know who I have fed and who I haven't, I have to move each one to a second box when I'm finished with her. Once they can jump out I will have to do something else. Hopefully they will be eating solid food before too long. But I've considered an alternate plan of putting a collar on the ones I've finished with--just while I am with them of course.

One kitten has decided to refuse to use the nipple on the bottle, so I am syringe feeding that one. So to tell which one it is, I put an ordinary sticker on her back (I have ladybug stickers) and it doesn't bother anything and then I can spot her easily!

This week will no doubt be a transition. Already they are showing that they can go potty by themselves, and sometimes actually go in the little cardboard make-shift litter tray I've set up in their box.

Sorry.

As of tonight they are out of the box and into a nice bed in one corner of my little laundry room. I made the move because they are starting to use the litter trays some of the time.

No doubt they will become more and more distinct and I'll be able to tell them apart.

Sincerely. Thank you. I've bottle fed kittens before and it is NO small commitment. Takes a lot of work and worry.

Will it be possible for someone to trap the feral mom and get her spayed?

Again - my sincere thanks and appreciation to you.

The lady who rescued the kittens said she'd keep trying.

Bottle feeding! A lot of work! Five times a day and with five of them to feed and "potty" it's 45 min each time not including washing bottles and mixing jars. But won't last much longer. In a week they'll be eating some solids hopefully!